This is one of those "it looked good on paper, but not in practice" stories...
We have river stones in between concrete pads leading to our garage. They're pretty, but the stones migrate for a few reasons:
- The driveway is on a slight incline. Stones like to roll downhill.
- It's pure sand between the concrete pads, so there's nothing substantial to hold the stones in place.
- If the car tires don't stay exactly on the concrete pads (and they don't), they push the stones around.
So the question is: how would you anchor the stones in place so they don't continually migrate? They don't have to be absolutely rigidly held in place -- maybe something semi-elastic would be ideal.